How to store a picture in a cloud of gas

By David Robson

IT’S like catching a moonbeam – using a cloud of vapour to capture images made of light itself. Right now, the result looks like something you’d see on a faulty LED display, but it could one day form the basis of a new type of computer memory.

First, rubidium atoms are exposed to a “pump” laser, putting them into an excited quantum state. This makes them transparent to pulses of light from a second laser, known as the “probe” beam, which carries information such as an image formed by shining the beam through a mask.

When the beams are turned off the atoms de-excite, at which point the final pulse of the probe beam is absorbed. This leaves an imprint in the atoms’ quantum states, which turns back into light when the pump beam is switched back on, allowing the image to be recovered. Since information is being stored and retrieved,

To continue reading this premium article, subscribe for unlimited access.